Residual Yield Research Articles

Effect of Elevated Temperatures on Mechanical Properties of Spliced and Non-Spliced Steel Reinforcements: Experimental Study

Steel reinforcement is an essential part of reinforced concrete, providing structural strength. In case of fire, the steel reinforcement severely loses its mechanical properties, leading to structural collapse in some elevated temperatures. Thus, this work mainly investigates the mechanical properties of spliced and non-spliced steel reinforcements after being exposed to 500 °C, 700 °C, and 900 °C. The results show that the mechanical properties of steel reinforcements significantly change after exposure to temperatures exceeding 500 °C, and the diameter of steel reinforcements does not considerably affect post-fire properties. The proposed equations from previous work were also compared to the testing results in terms of post-fire stress–strain curves and mechanical properties, resulting in overestimation at temperatures of 700 °C and 900 °C. The study finds that using a mechanical coupler has the potential to increase the residual yield strength at a temperature of 500 °C, but it lacks post-fire elongation at a temperature of 700 °C due to observed failure behavior after testing. Furthermore, the failure occurred at the mechanical couplers when the exposure temperature reached 700 °C. The modulus of elasticity of non-splices was the most critical parameter, which was maximally different by 23.9% compared to non-spliced steel reinforcements.

Valorization of Waste from Argan Seeds for Polyhydroxybutyrate Production Using Bacterial Strains Isolated from Argan Soils.

The aim of this work was to study the valorization of argan seed pulp, a waste material obtained from argan oil extraction, for the biosynthesis of polyhydroxybutyrate (PHB). A new species that showed the metabolic capacity for the conversion of argan waste into the bio-based polymer was isolated from an argan crop located in Teroudant, a southwestern region of Morocco, where the arid soil is exploited for goat grazing. The PHB accumulation efficiency of this new species was compared to the previously identified species 1B belonging to the genus Sphingomonas, and results were reported as dry cell weight residual biomass and PHB final yield measured. Temperature, incubation time, pH, NaCl concentration, nitrogen sources, residue concentrations, and culture medium volumes were analyzed with the aim of obtaining a maximum accumulation of PHB. UV-visible spectrophotometry and FTIR analysis confirmed that PHB was present in the material extracted from the bacterial culture. The results of this wide investigation indicated that the new isolated species 2D1 had a higher efficiency in PHB production compared to the previously identified strain 1B, which was isolated from a contaminated argan soil in Teroudant. PHB final yield of the two bacterial species, i.e., the new isolated and 1B, cultivated under optimal culture conditions, in 500 mL MSM enriched with 3% argan waste, were 21.40% (5.91 ± 0.16 g/L) and 8.16% (1.92 ± 0.23 g/L), respectively. For the new isolated strain, the result of the UV-visible spectrum indicates the absorbance at 248 nm, while the FTIR spectrum showed peaks at 1726 cm-1 and 1270 cm-1: these characteristic peaks indicated the presence of PHB in the extract. The data from the species 1B UV-visible and FTIR spectra were previously reported and were used in this study for a correlation analysis. Furthermore, additional peaks, uncharacteristic of standard PHB, suggest the presence of impurities (e.g., cell debris, solvent residues, biomass residues) that persisted after extraction. Therefore, a further enhancement of the sample purification during extraction is recommended for more accuracy in the chemical characterization. If 470,000 tons of argan fruit waste can be produced annually, and 3% of waste is consumed in 500 mL culture by 2D1 to produce 5.91 g/L (21.40%) of the bio-based polymer PHB, it can be estimated that the amount of putative PHB that can be extracted annually from the total argan fruit waste is about 2300 tons.

Corrosion Resistant Coating from Nano Printed Circuit Board Powder for the Reinforced Concrete Structures

Corrosion in steel leads to the deterioration of reinforced concrete structures due to chemical reactions between steel and its surrounding atmosphere. In this paper, a novel anticorrosive powder was derived from the waste Printed Circuit Board (PCB) and manually coated on the steel rebar of the reinforced concrete specimen. The corrosion-resistant efficiency of the developed nano PCB-coating on the steel bars was studied by polarization, electrochemical impedance spectroscopy, and accelerated corrosion technique. Also, the applicability of the nano PCB-coated rebar as reinforcement in the concrete environment was investigated. From the results, it was observed that the nano PCB-coated specimens exhibited 3.5 times reduced rate of corrosion and lost only 46.15% strength and 52.5% diameter under the accelerated rate of 6 V after 48 hours. The presence of nano PCB powder improved the corrosion-resistant behaviour of the steel rebar by 1.65 times of the noncoated specimen. Also, the nano PCB-coating reduced the loss in residual yield strength of the corroded steel rebar by 32% lesser than the noncoated specimens and exhibited similar corrosion-resistant properties as that of the existing zinc coating. In addition to the corrosion resistance, the nano PCB-coated steel rebar exhibited almost similar adhesion with concrete as that of the commercial zinc coating which is 7% lower than uncoated steel rebars. It was inferred from this research work that the proposed anticorrosive coating prepared from the waste nano PCB powder showed better corrosion-resistant behaviour and reduced the overall cost of coating by 42%, which ensures economy and serviceability.

Effect of Layered Aminovanadic Oxalate Phosphate on Flame Retardancy of Epoxy Resin.

To alleviate the fire hazard of epoxy resin (EP), layered ammonium vanadium oxalate-phosphate (AVOPh) with the structural formula of (NH4)2[VO(HPO4)]2(C2O4)·5H2O is synthesized using the hydrothermal method and mixed into an EP matrix to prepare EP/AVOPh composites. The thermogravimetric analysis (TGA) results show that AVOPh exhibits a similar thermal decomposition temperature to EP, which is suitable for flame retardancy for EP. The incorporation of AVOPh nanosheets greatly improves the thermal stability and residual yield of EP/AVOPh composites at high temperatures. The residue of pure EP is 15.3% at 700 °C. In comparison, the residue of EP/AVOPh composites is increased to 23.0% with 8 wt% AVOPh loading. Simultaneously, EP/6 wt% AVOPh composites reach UL-94 V1 rating (t1 + t2 =16 s) and LOI value of 32.8%. The improved flame retardancy of EP/ AVOPh composites is also proven by the cone calorimeter test (CCT). The results of CCT of EP/8 wt% AVOPh composites show that the peak heat release rate (PHHR), total smoke production (TSP), peak of CO production (PCOP), and peak of CO2 production (PCO2P) decrease by 32.7%, 20.4%, 37.1%, and 33.3% compared with those of EP, respectively. This can be attributed to the lamellar barrier, gas phase quenching effect of phosphorus-containing volatiles, the catalytic charring effect of transition metal vanadium, and the synergistic decomposition of oxalic acid structure and charring effect of phosphorus phase, which can insulate heat and inhibit smoke release. Based on the experimental data, AVOPh is expected to serve as a new high-efficiency flame retardant for EP.

Effect of nano cementitious composites on corrosion resistance and residual bond strength of concrete

The interconnection between the steel and concrete is frequently weakened by corrosion. Interestingly, it has been observed that nano pozalonic materials offer an economical approach for lowering the permeability of concrete by enhancing its morphological characteristics. This research discusses the impact of nano pozalonic materials on strengthening the corrosion resistance and pull-out behaviour of steel reinforcement in concrete. In order to treat concrete specimens with accelerated or immersion-based corrosion procedures, the cement is replaced with nanocement (NC) or nano fly ash (NFA).The performance of concrete is tested by evaluating its compressive strength, chloride ion penetration, corrosion potential, and water permeability. The steel reinforcement is examined to assess the residual yield strength and mass loss. In order to assess the bond-slip behaviour between concrete and the reinforcing steel, pull-out tests are performed. Our findings indicate that concrete with nano cement and nano fly ash exhibited excellent corrosion resistance by retaining the yield strength of reinforcement steel and corresponding bond strength.

Legume-based cover crop mixtures can overcome trade-offs between C inputs, soil mineral N depletion and residual yield effects

Cover crops can contribute to climate change mitigation through enhanced sequestration of atmospheric carbon dioxide into soil organic carbon. Few studies, however, have estimated the total carbon (C) input to soil, i.e. derived both from plant material (shoot and root) and phyllo- and rhizodeposition. Selection of cover crop species should account for multiple objectives, such as C inputs to soil, nitrate leaching reduction and positive residual effects on the following main crop. However, trade-offs between these objectives may occur. The aim of this study was to investigate the performance of the cover crop species winter rye, hairy vetch and oilseed radish, and to assess the ability of mixtures to overcome potential trade-offs. A randomized split-plot field trial was conducted to compare cover crop treatments and a weeded control under high and low soil nitrogen (N) availability. Multiple-pulse labeling with 14C-CO2 was carried out to trace net cover crop-derived rhizodeposition C. Soil mineral N was measured to 1.5 m depth in autumn, as well as grain and N yield in the subsequent spring barley.Cover crop species accumulated between 1250 and 2580 kg C ha−1, with significantly higher total C input (in shoot, root and phyllo- and rhizodeposits) for the mixtures compared with pure stands of either vetch or radish, while the results for rye were in between. The quantity of C lost via phyllo- and rhizodeposition (qClvPR) showed a significant positive correlation with root C and was highest for the mixtures and rye. The relative ClvPR ranged between 7% and 14% of total cover crop-derived C and tended to decrease under higher soil N availability. All cover crop treatments were able to decrease soil mineral N (0–1.5 m), with radish displaying the highest N leaching reduction potential. Despite substantial differences in cover crop total N uptake and C:N ratios, no significant differences were observed in the subsequent main crop grain or N yields. The mixtures showed the highest total C input and generally a higher or similar mineral N depletion potential than the average of the pure stands, suggesting that cover crop mixtures offer a realistic means for overcoming trade-offs among ecosystem functions.

Hybrid physics-BP neural network-based strength degradation model of corroded reinforcements under the simulated colliery environment

This study proposes a hybrid physics-artificial neural network (ANN)-based framework for developing a physics-based strength degradation model of corroded reinforcements taken from deteriorating reinforced concrete (RC) beams respective under a single harsh colliery environment and coupled action of corrosive environment and sustained load. This proposed degradation model can well account for the impacts of random variables (e.g., the diameter of reinforcing steel bars) on the strength degradation behavior of corroded reinforcements. The main contributions of this study include the following aspects: Firstly, based on the experimental results, a BP-ANN surrogate model is established to substitute the experiment method for generating the residual yield and ultimate strengths of corroded reinforcements under different exposure conditions. In addition, a new data sample is formed with the experimental and simulated data obtained by this trained surrogate model. Applying the Bayes theorem, the physics-based strength degradation model respecting to corrosion degree and diameter of corroding reinforcements is constructed. The posterior probability distributions of unknown model parameters are developed, which is beneficial for representing the epistemic uncertainty in assessing the service reliability of deteriorating RC components and structures. Finally, a sample from experimental data is randomly selected to verify the accuracy of this physics-based strength degradation model. Analytical results indicate that the diameter of reinforcements as well as the coupled action of corrosive simulated colliery environment and sustained load have considerable influences on the strength degradation of corroded reinforcing steels. This study provides an effective approach to developing a physics-based strength degradation model of corroding reinforcements and highly improves the use efficiency of experimental results.

Residual effect of biofortified iodine in soil, plant, crop yield and quality of tomato (Solanum lycopersicum L.)

When iodine levels in the soil are inadequate, resulting in limited crop uptake and as a result, a population with insufficient iodine intake. Iodine deficiency can be avoided by biofortifying commonly consumed crops with iodine. Tomato is the best crop for biofortification study as it is having the capacity to store excess iodine in pholoem. The field experiment was carried out in Thondamuthur block of Viraliyur village at Coimbatore district of Tamil Nadu in 2021. The purpose of this study was to determine the effect of biofortication of iodine in residual tomato growth, yield, quality and iodine content. Potassium iodate and Chitosan were applied in the form of soil, foliar and Chitosan iodate complex at different stages of plant growth. The results revealed that the soil fertilization of potassium iodate alone resulted in lower uptake of residual iodine in fruits because the iodine was susceptible to high volatilization and less phyto-availability. While foliar spray alone increased the residual iodine content in roots and stem. However, residual higher iodine accumulation in the tomato fruits was achieved through the combination of foliar and iodine Chitosan forms. As electrostatic interaction between Chitosan and iodate prevents volatilization and gradually increases the bioavailability of iodine from soil to fruits. Based on the discussion, biofortification of iodine through potassium iodate Chitosan complex paved the way for the improvement of growth, yield, quality and iodine content in fruits. Hence, biofortification of iodine through iodate Chitosan complex increased the iodine content in tomato fruit and introducing it in our daily diet may be helpful to reduce iodine deficiency disorder.

Post-fire mechanical response of Q960E ultra-high-strength structural steel

The ultra-high-strength steel (UHSS) has gained significant attention in recent years owing to its prominent benefits in structural performance, economics and environmental aspect. The fire resistance of steel structures is always of great concern as the mechanical properties of steel are sensitive to high temperatures which could threaten the safety of the steel structures, and so do UHSS structures. The post-fire mechanical performance of steel is crucial for evaluating the residual capacity of the structure. Therefore, it is also necessary to evaluate the post-fire mechanical properties of UHSS. In this study, tensile tests were carried out to investigate the post-fire mechanical properties of Q960E UHSS with two types of cooling techniques, i.e. cooling in air or cooling in water. The residual elastic modulus, yield stress, tensile strength, tensile strain, rupture stress, and percentage reduction of area of Q960E UHSS subjected to various temperature levels were obtained from the post-fire stress-strain curves. The influence of the cooling techniques and temperature level on the post-fire mechanical properties of Q960E UHSS were discussed, and some empirical predictive equations were proposed for evaluating the post-fire mechanical properties. Finally, a novel stress-strain model was also proposed to predict the post-fire response of Q960E UHSS. The proposed model showed good consistency with laboratory experimental results. Therefore, it is concluded that the model can provide accurate predictions for the plastic strain-true stress curve for various types of steels.

Influence of in‐situ growth of boron nitride with chestnut ball copper cobaltate synergistic ammonium polyphosphate on flame retardancy, smoke suppression, and thermal conductivity of polylactic acid

AbstractAmmonium polyphosphate (APP) is generally used to prepare fire retardant polymer composites, but it is still a challenge to further improve its flame retardant efficiency. In this study, BN‐CuCo2O4 (BNCC) hybrid was successfully prepared by in‐situ growth of copper cobaltate (CC) on boron nitride (BN) by the hydrothermal method. It was added together with APP to polylactic acid (PLA) to prepare PLA composite materials. Investigations were performed into its influence on the composite's fire‐retardant ability and thermal conductivity. When 3 wt% BNCC and 12 wt% APP was added, the limiting oxygen index (LOI) of the PLA composite reached 31.7%, which was higher than that of pure PLA improved by 69.5% and it reached V‐0 rating of vertical combustion test (UL‐94). The cone calorimeter (CCT) test showed that the addition of 3 wt% BNCC and 12 wt% APP to PLA composites significantly increased both the residual char yield and the efficiency of suppressing smoke production compared to pure PLA and APP/PLA composites. BNCC could further improve its flame retardant efficiency of APP. The thermal conductivity test showed that BNCC further improved the thermal conductivity of PLA composites. Furthermore, the residual char and fire‐retardant mechanism of the composites was analyzed and intensive studied.

Post‐fire Residual Strength and Ductility of Structural Steels from Hollow Sections

AbstractSteel structures are severely affected by the extreme temperatures reached during a fire. After this, if the structure has not collapsed, the remaining elements can be reused if they are not excessively distorted or the material is still fit for service. In the last case, residual properties of steel must be adequate and fulfil the requirements of the current standards. On this matter, it is hypothesized that residual behaviour of steel not only depends on the highest temperature reached during the fire episode, but also on the load it was simultaneously bearing.This work is focused on an experimental study on the post‐fire behaviour of structural steels. Specimens were cut from structural steel (S355) cold‐formed circular hollow sections (CHS) and subjected to a combination of tensile stress and high temperature. Afterwards, the specimens were cooled in air back to room temperature and, finally, load was increased until specimen failure. The obtained results allowed discussing on the residual yield strength, ultimate strength and stiffness of the steel, and a special focus was put on the residual ductility. The results of this work can provide a basis to the appraisal of steel structures after fire, supporting the further decision on its reinstatement or subsequent demolition.

Modelling residual stress and residual work hardening induced by surface mechanical attrition treatment

Shot peening induced residual stress is strongly related to residual work hardening which relies on both the process and the target material. In this work, residual stress and coupled residual work hardening are studied in a surface mechanical attrition treatment (SMAT) on a cylindrical structure by combining discrete element method (DEM) and finite element method (FEM). Shot, ultrasonic parameters, chamber structure, sonotrode surface, and cylindrical structure of the target are finely modeled in DEM simulation. On the basis of the DEM results, FEM simulation of the SMAT process is performed on a representative area considering the factual impact parameters and elastic-plastic behavior of the target material, and mechanism of residual stress generation is analyzed. It shows that isotropic hardening and kinematic hardening of the target material play a different role in residual stress generation. The obtained maximum compressive residual stress is mainly determined by residual yield stress, while the residual kinematic hardening is nearly unchanged when the coverage is increased. Further analyses indicate that the mechanisms of residual stress generation should be very different for the Johnson-Cook model and the model that includes kinematic hardening, even though these two kinds of models are reported to be able to well predict the shot peening induced residual stress. The gradient of the residual work hardening can be used for further evaluating mechanical properties of the SMATed cylindrical structure.

Enhanced flame retardant performance of rigid polyurethane foam by using the modified OMMT layers with large surface area and ammonium polyphosphate

A phosphorus-containing organosilicon compound (PCOC) was synthesized and used to modify organic-montmorillonite named M-OMMT. The results showed that the interlayer spacing of the intercalated M-OMMT layers became larger and the exfoliated M-OMMT layers were connected by PCOC after the modification. Then, M-OMMT was combined with ammonium polyphosphate (APP) to improve the flame retardancy of rigid polyurethane foam (RPUF) composites. The thermal stability and flame retardancy of RPUF with M-OMMT and APP was lucubrated using thermogravimetric analysis (TGA), limited oxygen index (LOI) and cone calorimeter test. After the addition of modified OMMT layers, the Td,5%, Tmax1 and Tmax2 of RPFU/APP/M-OMMT (234 °C,304 °C and 462 °C) were all higher in contrast to RPUF/APP/OMMT (223 °C, 298 °C and 454 °C). Compared with RPUF/APP/OMMT, the peak heat release rate and total smoke release of RPUF/APP/M-OMMT were apparently reduced from 292 kW/m2 and 552 m2/ m2 to 156 kW/m2 and 350 m2/ m2, and the residual char yield increased by 37%. The SEM results showed that the addition of M-OMMT promoted the formation of a more compact and intumescent char layer. After the modification of PCOC, the layers of M-OMMT overlapped each other to form a larger surface area, which can exert a better physical barrier and protective effect together with APP on RPUF, fabricating the RPUF/APP/M-OMMT composite with the good flame-retardant property.

Metal salts used as an efficient catalyst to reduce the ring opening polymerization temperature of benzoxazines

An attempt was made to develop low-temperature curing aniline-based benzoxazines (BA-a/BF-a) using various transition metal salts, such as FeCl3, CoCl2, NiBr2, CuCl2, ZnCl2, Zn(OAc)2, CdCl2 and Alkali–Alkaline earth metal salts, such as LiCl, KI and CaCl2 and main group metal salt AlCl3 as an efficient catalyst. The findings of the DSC analysis revealed that the main group and transition metal salts had outstanding catalytic activity and were able to reduce the curing temperature of benzoxazines (BA-a/BF-a). Among the various metal salts, FeCl3, AlCl3, ZnCl2 and Zn(OAc)2 exposed excellent catalytic behavior in lowering the curing temperature of benzoxazines to 145 °C (BA-a) and 150 °C (BF-a) from 217 to 218 °C, respectively. The thermal stability and flame retardant characteristics of the resultant polybenzoxazines (PBz’s), are also studied and included in this work. In the presence of catalysts, the initial degradation temperature almost same, residual char yield increased from 27 to 55%, and the flame retardant properties increased to 39.5 from 28.5 for the resultant PBz’s.

Residual Soil Fertility, Nutrient Uptake, and Yield of Okra as Affected by Bioorganic Nutrient Sources

ABSTRACT A two-year experiment was undertaken during kharif seasons of the year 2019 and 2020 to investigate the effect of bioorganic nutrient sources (farmyard manure, vermicompost, jeevamrit, and ghanjeevamrit) and inorganic fertilizers on residual soil fertility, nutrient uptake, and fruit yield of okra in Entisols of Himachal Pradesh. The experiment consisted of nine treatments with varying combinations of nutrient sources. Treatment T3 [jeevamrit application (100% N equivalence) + farmyard manure @ 10 t ha−1] resulted in highest residual soil organic carbon (12.00 g kg−1), culturable microbial count (69.67 cfu g−1 soil × 105), microbial biomass carbon (67.43 mg kg−1) and nitrogen (37.40 mg kg−1) as well as maximum plant-available N (309.3 kg ha−1), P (23.2 kg ha−1), K (187.9 kg ha−1), S (60.3 kg ha−1), Fe (15.55 mg kg−1), Cu (1.92 mg kg−1), Mn (11.73 mg kg−1) and Zn (1.62 mg kg−1) contents. Further, the treatment T6 [jeevamrit application (100% N equivalence) + vermicompost @ 2.5 t ha-1] obtained the greatest value for okra yield (11.95 t ha-1) along with more uptake of macro and micro nutrients by the plants. This superior combination (T6) recorded an increase of 21.3% in yield over T2 (RPMF) as well as the highest net returns (₹ 1,50,258/ha) and B:C ratio (2.69). Thus, it can be inferred that the conjoint use of jeevamrit (100% N equivalence) with farmyard manure or vermicompost is beneficial for improving residual soil fertility, nutrient uptake, and sustainable okra production with 100% net saving of fertilizers.

Test on post-fire residual mechanical properties of high strength Q690 steel considering tensile stress in fire

As a steel building may not fail in a fire scenario, the residual mechanical properties of steel after fire exposure are essential in evaluating the post-fire performance of the steel structure. However, the current experimental research regarding the post-fire mechanical properties neglects the stress in steel during the heating and cooling phases, which violates the fact that a steel structure still carries load during a fire hazard. In order to quantitatively assess the influence of stress level in steel structures on post-fire residual mechanical properties of high strength steels, a series of tensile tests was carried out on a typical high strength Q690 steel specimen exposed to elevated temperatures under three stress ratios, namely 0.30, 0.55 and 0.80. During the heating and cooling phases, constant stress was applied on the specimen to simulate the possible stress in steel structures in fire hazards. After cooling, tensile tests were carried out to attain the post-fire stress-strain curves of Q690 steel, and accordingly determine the residual yield strength, ultimate strength and elastic modulus of Q690 steel with different temperature exposures and stress levels. The test results show that the tension stress in steel during heating and cooling can improve the post-fire yield strength and ultimate strength of Q690 steel with the maximum 8% when the exposed temperature is lower than 700 °C, and the improvement increases as the stress level increases. However, the tension stress has adverse effect on the post-fire strengths of Q690 steel when the exposed temperature reaches 800 °C. If the exposed temperature is below 700 °C, it is safe to take the original strengths of Q690 steel to evaluate the post-fire performance of Q690 steel structures. However, the stress effect on the residual strengths should be considered if the exposed temperature reaches 800 °C to avoid unconservative evaluation. The tension stress in steel has no significant influence on residual elastic modulus of Q690 steel. By comparing the obtained test data with other post-fire tests on similar steels, it is found that the post-fire residual mechanical properties of steels are different even if those steels have the same nominal yield strength. The maximum 40% dispersion for residual yield strength and 50% dispersion for ultimate strength are found when the exposed temperature surpasses 600 °C due to rolling, quenching and tempering for high strength steels.

Characterization of Spent Coffee Grounds in the Community as Supporting Materials for Renewable Energy

Coffee grounds are a by-product of the coffee brewing process. Currently, coffee grounds in the community are still untapped waste. Whereas spent coffee grounds has the potential to be converted into various high value bio-products that are environmentally friendly. This study aims to characterize coffee grounds waste which is popular in the community as a supporting material for renewable energy. This study uses a comparative method of 3 samples of Arabica coffee grounds (SCG-A), Robusta (SCG-R), and the Arabica-Robusta blend (SCG-AR) from coffee brands that are popular in Indonesian. Quantitative analysis was carried out by comparing the percentage of residual yield of the three samples. Qualitative characterization of coffee grounds was carried out using the FTIR 8300/8700 Spectrophotometer. The results of the three samples showed different rendemen values, namely 70% SCG-A, 60% SCG-R, and 80% SCG-AR. The FTIR test results showed that the three spent coffee grounds had the same functional group characteristics in the frequency range of 650–3900 cm-1. The detection of the hydroxyl functional group (-OH), the asymmetric strain of the CH bond of the methyl group (-CH3), and the stretching vibration of CO in the COH bond found in coffee grounds waste shows its potential as a supporting material for renewable energy if a further process is carried out in the form of pyrolysis/calcination at room temperature. 700◦C. Utilization of spent coffee grounds in the community can be done by establishing a Spent Coffee Grounds Bank (SCG Bank), educating the public so that they are willing to donate spent coffee grounds, and managing SCG as a supporting material for renewable energy.

The rapid pyrolysis feature and evolution of heteroatoms of Indonesian oil sand

The rapid pyrolysis behavior of a kind of Indonesian oil sand was studied by a fixed-bed reactor. According to X-ray photoelectron spectroscopy (XPS), 1H nuclear magnetic resonance spectra (1H NMR) analysis, the organic structure model of oil sand and the occurrence of heteroatoms were proposed. Liquid products were characterized by gas chromatograph with mass spectrometer (GC-MS) and atomic emission detector for gas chromatography (GC-AED). In addition, the distribution of the gaseous product was analyzed using gas chromatograph (GC). During the rapid pyrolysis process, the tar yield reached its maximum at 450 °C, and the gas yield increased rapidly with the increasing temperature, while the residual sand yield displayed the opposite trend. Aromatic esters and aliphatic hydrocarbons were the predominant components of liquid products after rapid pyrolysis treatment. More stable heteroatom compounds, such as thiophene and furan, would be released into liquid product with an elevated pyrolysis temperature. Atoms like sulphur and oxygen on the aliphatic side chain were easily transformed into gaseous products such as H2S, CO2 and CO. Sulfur-containing compounds in oil sand minerals converted from sulfate to metal sulfide during the pyrolysis process. After thermal decomposition, heteroatoms compounds in organic matter transferred to gaseous product or liquid product along with the volatiles. However, heteroatom compounds in inorganic substances presented in residual sand in a more stable form.

Fatigue Behavior of Heavy-Haul Railway Prestressed Concrete Beams Based on Vehicle-Bridge Coupling Vibration.

Due to the demand for increasing trainload and enhancing some existing heavy-haul railways, the low reserve value of bearing capacity is a problem for the 32 m-span simply supported beam. The fatigue behavior of prestressed concrete beams in a heavy-haul railway loaded by 33 t and larger axle weight of trains was experimentally investigated. The experimental results of the fatigue behaviors, including fatigue deformation, crack propagation behavior, and strains of classical materials were obtained and analyzed. A fatigue behavior assessment model was established to investigate the residual stiffness and yield point degradation of the beams loaded by the trainload. The effects of train fatigue cycles and prestress loss on the residual stiffness and yield point degradation models of the beams were analyzed. The results indicated that the crack development process had three stages during the fatigue process: the derivative stage, gradual development stage, and fatigue failure stage. Trainload was the main external factor influencing the fatigue behavior of prestressed concrete beams. The increase in trainload accelerated the degradation rate of the residual stiffness of the beams and yield point, reducing the fatigue life. The prestressing strand was primarily used to delay the concrete cracking in the tension zone. When the beam was not cracked, the prestressed concrete beam showed good fatigue performance, and the degree of prestressing did not affect the fatigue life of the beams. When the maximum fatigue load exceeded the cracking load of the beam, prestress loss in beams became a critical issue that accelerated the degradation rate of fatigue strength and reduced fatigue life. The higher the fatigue damage degree, the more pronounced the effect of prestress loss on the fatigue strength of the beams. The fatigue failure of prestressed concrete beams occurred in the bottom tensile steel bar. Therefore, when the trainload of a heavy-haul railway is greater than the cracking load of the beam, it is recommended to strengthen the beam by prestressing and strictly control the trainload to avoid yield failure.

Residual seismic capacity of beam-column components with corroded reinforcement

Several concrete structures in tectonically active regions of the world are exposed to chloride ingress from seawater, saltwater, and other sources, making them vulnerable to corrosion-induced deterioration. Although it is well-known that corrosion-induced deterioration influences the force-displacement behaviour of corroded concrete components under cyclic loading, no adequate provisions have been incorporated into state-of-practice seismic assessment procedures to account for the influence of corrosion on the modeling parameters and acceptance criteria for concrete components. Using an extensive database of 418 material-level and 271 component-level test specimens with deformed bars, this paper presents simple formulations for evaluating the residual yield strength, ultimate strength, ultimate strain capacity, and bond strength of corroded deformed bars. Conclusions from the material-level study are then used in proposing approaches for predicting the flexural strength, shear strength and failure mode of beam-column components with corroded deformed bars. Subsequently, a simple reduction factor formulation is proposed for predicting corrosion-induced deformation capacity deterioration in corroded concrete components. The proposed reduction factor is demonstrated to be applicable to current deformation capacity formulations in ASCE/SEI 41–17 and Eurocode 8.